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Each entry on the list consists of the following information
JIRA issue key, TFS work item id
JIRA issue and TFS work item identifiers for which a synchronization failed. One of the identifiers may be empty, if an error occured when trying to synchronized an issue/work item that has not been paired yet (for example when creating a new issue/work item).
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For every error entry there are two available operations
Acknowledge (forget)
Clicking on Acknowledge removes an entry You can click on Acknowledge link in order to ignore the error and remove it from the list. Note however, that it will reappear after the next failed synchronization attempt.
Force resynchronization
Clicking on Force resynchronization forces TFS4JIRA Synchronizer to retry synchronization at the next profile run.